Why 35?

To the Point- nothing crazy happens when you turn 35, but there are historical reasons behind this non-magic number…

To understand why age 35 seems to be such a big deal, we have to go back into some prenatal genetic testing history. Before 2007, the American College of Obstetrics and Gynecologists (ACOG) recommended that all women 35 or older at the time of delivery be offered prenatal diagnostic testing such CVS (chorionic villus sampling) or amniocentesis. As noted above, nothing crazy happens when mom turns 35, but at 35, the chance of having a baby with an age-related chromosome abnormality is approximately 1 in 200 (0.5%, < 1%) and the chance of having a miscarriage from an amniocentesis was thought to be about 1 in 200 as well. Since the chance of the baby having an age-related chromosome abnormality when mom is less than 35 is lower than the risk of miscarriage from amniocentesis, it was deemed inappropriate to offer invasive testing like CVS and amniocentesis to women younger than 35.

For multiple reasons, the American College of Obstetricians and Gynecologists (ACOG) recommendations were changed in 2007. At that time, they decided that mom’s age of 35 or older at delivery should not be used as a cut-off in determining who does and does not get offered amniocentesis and CVS (and other screening tests, as well). The attitude had shifted towards acknowledging the fact that patients have different beliefs and values and may or may not want to get definitive answers regarding chromosome abnormalities during the pregnancy, regardless of their age.